It's the coldest night Berlin has seen in the best part of six months, so it's perhaps understandable when people aren't overly eager at first to linger on the forecourt of a gas station to talk to a reporter.

The filling station on Skalitzerstrasse, in the German capital's Kreuzberg district, is doing a steady if less than intense trade. Yet those who do pull up to refuel their cars are giving the diesel pumps plenty of attention.

When the topic of diesel bans and retrofits is raised with the customers, they are surprisingly willing to put up with the cold for a few minutes more to give their opinion. These are delicate times for Germany's diesel drivers, after all.

Only a real glutton for punishment would wish to hear a full retelling of Germany's diesel woes of recent years. The simple version is that after 15 years of relentless growth and popularity amongst drivers, the fuel — and especially the vehicles powered by it — has been somewhat hunted politically since the September 2015 Volkswagen Dieselgate emissions scandal.

In February 2018, Germany's top administrative court paved the way for bans on diesel cars and in May, Hamburg became the first German city to enact a partial ban.

Diesel debate a 'political game'

The political and industrial debate over what to do with older diesel cars — particularly those spewing out high levels of nitrogen oxide (NOx) — is reaching a critical stage in Europe's car-loving heartland. Talks are ongoing between German government representatives and carmakers over how to handle the politically-sensitive topic, with expensive retrofits firmly in the pipeline.

Mike, a 44-year-old working in the energy business in Berlin, is happy to talk before he hops back into his three-year-old diesel-powered Mercedes. A so-called 'Euro 6' standard diesel, it is not the kind of car that would be in line for an expensive retrofit under the measures currently being discussed.

Read more: Porsche ditches diesel for good amid VW fallout

A long-term diesel driver who prefers the fuel to gasoline for its superior efficiency, Mike sees the current debate as "a political game."

He believes that any retrofitting that takes place should be paid for by the German government, regardless of how expensive it is. He also believes any banning of older diesels would be completely out of order, and highlights the importance of diesel as a commercial fuel.

"A lot of things are transported via diesel, so there is a benefit from that," he says. "Politicians are responsible for many things working well in a democracy, not just scoring green political points. Business needs to work well too."

Fueling efficiency 

It's a point which chimes on the forecourt. As Ulli pumps air into the tires of his dainty-looking Smart car, it's easy enough to ascertain that he is not a diesel driver.

Yet he agrees that diesel's importance as a fuel for business owners reliant on efficient methods of transport needs to be emphasized.

"Gasoline just doesn't make sense if your business involves driving — and most do," he tells DW.

The latest reports from the government talks, coming from the German business daily Handelsblatt, suggest that car owners may have to cover up to €600 of the costs of a €3,000 retrofit, with manufacturers covering the remainder.

"The taxpayer shouldn't have to pay for that, the companies have to pay for that. They were the ones who messed up," says Ulli.

As for the idea of older diesels being deemed unroadworthy before they have reached their natural end, it's an idea that he believes would amount to "expropriation."

"That's the word if you bought something, like property or a car, and then they tell you that you can't have it anymore, after you have paid for it," Ulli says. "That simply cannot be."

Why give up your car and lose money?

Ben, a 33-year-old New Zealand expat is filling up his car. He says that diesels are "dirtier," but he also understands why political attempts to make them intolerable are so unpopular with ordinary drivers.

"They are very easy on the wallet and they do go a long way. So it is hard for people to switch when they know they are basically going to lose money."

For practically all the drivers DW spoke to, that is the overwhelming point they make about the fuel.

Read more: Berliners react to diesel's possible demise

"I have almost always driven diesels," says Jens, a 41-year-old who tells DW he works in the German car industry.

"Diesel is significantly cheaper than gasoline, which incidentally is also due to the government because of the tax benefits given to it," he says. "With the consumption and efficiency the way it is, it makes no sense for us currently to change to gasoline."

He believes much of the current discussion on diesel in Germany is "political" and "as with most political discussions, the discussion about diesel is not factual."

Call for a wider debate on air pollution

Jens says a more fundamental debate on Germany's urban air quality is needed, and that the excessive focus on diesel somewhat muddles the issue.

"Is diesel the main cause of bad air in the cities? No, I would not say that as there are many offenders. But no question: less older diesels means better air, there is of course a connection there," he admits.

"But to basically demonize the diesel now in my opinion is not right, especially since current new diesel models, when you look at the overall balance of pollution, are certainly not worse than other types of engines."